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Difficulty: MediumAuthor's Primary Purpose

Read the three technical excerpts below. Match each passage to the statement that best expresses the author's primary purpose.

  • High-pressure hydraulic lines operate under extreme pressures exceeding 3,000 psi. Never use bare hands to inspect for pinhole leaks, as pressurized fluid can penetrate human skin and cause severe tissue necrosis. Maintenance technicians must always depressurize the system and utilize cardboard or wood shields during leak inspections.To caution maintenance personnel against hazardous inspection practices and prescribe safety protocols.
  • When a marine propeller rotates rapidly through water, localized low-pressure zones develop along the blade's suction surface. If the pressure drops below the vapor point of water, micro-bubbles form and immediately collapse against the metal alloy. This violent collapse generates shockwaves that gradually pit and erode the blade structure.To explain the physical mechanism by which fluid pressure changes cause mechanical surface damage.
  • Prior to the widespread adoption of the snorkel mast, diesel-electric submarines were required to surface completely to run their engines and recharge battery banks, exposing them to radar detection. The snorkel allowed vessels to draw fresh combustion air while remaining submerged at periscope depth, fundamentally transforming diesel submarine survivability.To outline how a technological innovation resolved an operational vulnerability in naval history.

Answer

Match the hydraulic fluid passage with the purpose of cautioning personnel against hazardous practices; match the marine propeller passage with the purpose of explaining the physical mechanism of surface damage; and match the submarine snorkel passage with the purpose of outlining how a technological innovation resolved an operational vulnerability.
Each excerpt has a distinct rhetorical function: the first provides imperative safety rules for workplace hazards, the second details the physical cause-and-effect mechanism of cavitation erosion, and the third describes a historical technological adaptation that solved a tactical vulnerability.

Step-by-Step Solution

1
Analyze the main focus and rhetorical tone of the first passage on hydraulic lines.
The text emphasizes physical risks ('tissue necrosis', 'never use bare hands') and mandatory safety rules ('must always depressurize', 'utilize cardboard').
Identifying imperative verbs and safety warnings reveals that the author's primary intent is preventive safety and procedural guidance.
2
Analyze the main focus and rhetorical structure of the second passage on propellers.
The text describes a cause-and-effect physical sequence: rotation leads to pressure drop, forming vapor bubbles whose collapse causes pitting.
Identifying the objective, scientific explanation of a physical process confirms the author's intent to explain how cavitation damage occurs.
3
Analyze the main focus and rhetorical structure of the third passage on submarine snorkels.
The text contrasts an old historical limitation (surfacing to recharge) with the solution provided by snorkel masts to increase submerged survivability.
Identifying the historical context and technological solution confirms the intent to profile an innovation that addressed an operational tactical flaw.

Key Concept

Author's Primary Purpose
Estimated Time:1m 30s
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